The present invention refers to a process for forming an annular stack of laminations for the stator of an electric motor of the linear type, particularly for the mutual fixation of the metallic laminations of the annular stack of laminations.
In the manufacture of a hermetic compressor for refrigeration with a linear motor, there are several components that constitute the compressor, one of them being the linear motor. This type of motor consists of an assembly of metallic laminations made of steel, which are radially packed, forming the stator of the electric motor on which is wound a copper wire, in order to form the induction coil of the motor.
The linear motor further has another assembly of metallic laminations, which also forms a radial stack, denominated external annular stack, which defines, with the stator, an annular space inside which moves the magnetic impeller, whose function is to produce the linear movement of the piston of the compressor, so that said piston may provide gas compression inside the cylinder of the compressor.
Some processes for forming the annular stack of metallic laminations for the stator of an electric motor of the linear type are well known. In one of said processes, the metallic laminations are individually and manually positioned in a cylindrical body, in order to form the annular configuration. In this positioning process, it is not possible to assure the radial orientation of the metallic laminations (even if an auxiliary circumferential belt is used for the assembly), which orientation is important for a good performance of the compressor. The way used for achieving the orientation of the metallic laminations in a uniform radial arrangement in this process of forming the annular stack of laminations is to submit said laminations, after they are placed on the cylindrical body, to a magnetic field, for forcing said metallic laminations to the correct formation, maintaining this distribution until said metallic laminations are affixed in said configuration. In this process, the fixation of the metallic laminations in an annular configuration in the lamination stack is achieved by gluing said laminations after the magnetic field is applied for alignment. This is a complex process, involving many operational steps and requiring much labor, which increases the manufacturing costs.
In another known process for forming the annular stack of laminations (U.S. Pat. No. 5,945,748), the metallic laminations are each provided with a slot in a portion of one of its end edges. Said slots define, upon the circumferential alignment of said metallic laminations, a circumferential housing for receiving a retaining ring. This construction requires, necessarily, the formation of the annular stack of metallic laminations and the radial orientation thereof before the retaining rings are placed.
Thus, it is an object of the present invention to provide a process for forming an annular stack of metallic laminations for the stator of a linear motor, which allows obtaining and maintaining a correct and aligned positioning of the metallic laminations of said lamination stack, without the disadvantages of the known techniques, further allowing the fixation between the metallic laminations of the lamination stack to be achieved before the formation of the annular stack of metallic laminations.
This and other objectives of the present invention are achieved by a process for forming an annular stack of metallic laminations for the stator of a linear motor, from a plurality of metallic laminations, which are radially positioned and have an internal edge and an external edge, said process comprising the steps of: axe2x80x94providing a rectilinear alignment for a plurality of metallic laminations which are laterally and mutually seated, with their internal edges defining a flat surface; bxe2x80x94affixing to each other the internal edges of the rectilinear alignment of the metallic laminations, in order to allow only the relative and limited angular displacement of each metallic lamination around its respective internal edge; and cxe2x80x94deforming the alignment of the metallic laminations affixed to each other to an annular configuration, with the internal edges of the metallic laminations defining an internal cylindrical surface of said annular stack.
It is a further object of the present invention to provide an annular stack of metallic laminations, such as that considered above.